Refrigerating apparatus



y 1930- Q o. c. OLSEN 1,768,625

REFRIGERATING APPARATUS Filed March 30, 1929 Patented July 1, 1930UNITED STATES PATENT OFFICE OLAI' C. OLSEN, OF DAYTON, OHIO, ASSIGN OBTO FRIGIDAIRE CORPORATION, 0]? DAY- TON, OHIO, A CORPORATION OF DELAWAREBEFBIGERATING APPARATUS Application filed March 30, 1929. Serial No.851,287.

This invention relates to refrigerating apparatus and particularly toarrangements for controlling the circulation of refrigerant in such aparatus.

One 0 the objects of the invention is to provide an improved controldevice particularly adapted to multiple installations whichautomatically prevents the circulation of refrigerant in such unit orunits of the system as do not need refrigeration.

Another object of the invention is to provide an improved refrigeratingsystem in which one condensing element supplies a number of evaporatingelements with refrigerant and automatically maintains each of themwithin predetermined temperature limits independent of the remainingelements.

More specifically it is an object to provide an improved form ofautomatic control valve for positivel closing the outlet of anevaporator when t ere is no refrigerating demand upon such evaporator.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanying.drawing, wherein a preferred form of the present invention is clearlyshown.

In the drawings:

Fig. 1 is a diagrammatic representation of one form of refrigeratingsystem embodying my invention,

Fig. 2 is a control valve, partly in section and partly in elevation,

Fig. 3 1s a plan view of a portion of the valve,

Fig. 4 is a section on the line 44 of Fig. 3,

Fig. 5 is a section on the line 5-5 of Fig. 3,

Fig. 6 is a section on the line 6-6 of Fig. 3, and

Fi 7 is a section on the line 77 of Fig. 3.

It has previously been proposed to provide a number of-evaporators whichare supplied with refrigerant from a common condensing element and tooperate the system so as to maintain the different evaporators atdifferent temperatures. 1 In the usual systems of this character thedifferent evaporators are not' entirely independent of each other andthe condensing element does not circulate refrigerant through thevarious evaporators in accordance with the refrigerating demand uponeach. The difficulties experienced have been the more pronounced incases in which it is sought to maintain widely different temperatures.My invention is concerned with providing a simple, economical andimproved control valve which will satisfactorily maintain widelydifferent temperatures and which will enable the various refrigeratingelements to be operated independently of one another.

Referring to the drawing 10 designates in general a condensing elementfor withdrawing gaseous refrigerant from a vapor conduit 11, liquefyingthe refrigerant and delivering it to a liquid supply conduit 12. Thecondensing element may be of any desired type, for example it mayinclude the usual motor 14, compressor 15 and condenser 16, the motorbeing actuated in response to the pressure within the conduit 11 bymeans of an automatic switch 18 which connects the motor to power mains19. Evaporators 20 and 21 are connected in parallel between the liquidsupply conduit and the vapor exhaust conduit 11 for cooling compartments20 and 21. The evaporators are connected to the conduit 11 by means ofindependent outlet conduits 23 and 24. Preferably each of theevaporators is of the flooded type and includes a reservoir for liquid.refrigerant which is kept at a constant level therein by means of afloat valve, not shown herein, but fully disclosed in the patent toOsborn 1,556,708, October 13, 1925. Since the evaporators are of theflooded type, the pressure of the refrigerant in each will correspond toits temperature. Assuming that the evaporator 21 is to be kept at thehigher temperature and pressure, I place in the outlet of thisevaporator a shut-off valve 26, the construction of which is illustratedin Figs. 2 to 7, and which automatically closes when the evaporator 21has reached a predetermined low pressure. A valve casin 30 having aninlet 31, an outlet 32, and a ore 33 is connected between the conduit 24and conduit 11. Within the casing is a valve seat 27 and a valve properwhich is either raised to permit unrestricted communication between theinlet and outlet, or else is lowered against the seat to positivelyclose the outlet, by means about to be described. To the casing issealed the open end of a flexible metal bellows 35, the other end ofwhich is closed in any suitable manner. Preferably the bellows is closedat its upper end by a cap 36 soldered to the bellows and its lower endis soldered to an end cap 37 secured to the easing in any suitablemanner. The bellows form a motor for operating the valve 25 in responseto the pressure within the casing 30 thru an actuator 39.

The actuator or rod 39 is rigidly secured to the bellows cap 36 andextends down into the bellows where it has a lost motion connection withthe valve 25. This is preferably formed by a bore 40 which receives areduced portion 41 of the valve stem, the bore having a slot 42 in itswall to receive a pin 43 in the valvestem. The valve is normallyprevented from movement by a pair of friction shoes 48 urged outwardlyagainst the bore 33 by a spring 49. There is sufficient clearancebetween the valve stem and bore to permit the pressure in the bore to befreely communicated to the bellows, the bore however serving as a guidefor the valve.

The rod 39 extends above the cap 36 and at its upper end has a reducedportion 50 on which a nut 51 clamps cam members 52 and 53. Each of thecam members, as shown in Figs. 3 to 7, is preferably provided with anumber of radial lugs, arranged in pairs. Each pair has oppositelydisposed faces of the same slope, and the slope of the pairs isdifferent.

Thus in Fig. 4, the faces have a relatively small inclination to thevertical, while the inclinations of the pairs of faces 61, 62 and 63progressively increase.

A pair of cam followers are pivoted to lugs 71 on a frame 72 secured tothe valve casing. The followers have rollers 73 which are urged a ainstthe cam faces by a pair of springs 75 and a tie rod 76 whose effectivelength can be varied to adjust the tension of the springs by nuts 78.

The valve operates as follows. In the position shown in Fig. 2, thevalve is closed and is positively held closed by the pressure of the camfollowers on the cam 52. As the pressure in the valve casing increases,the bellows expands gradually lifting the rod 39 and forcing the camfollowers farther apart, increasing their potential energy stored in thesprings 75. During this gradual movement, the slot 42 moves along thepin 43, the valve remaining stationary due to the pressure in the casingand the friction shoes 48. At a predetermined point in the expansion ofthe bellows the cam followers reach the dividing line between the cam 52and cam 53, and substantially all of the lost motion in the connect-ion42-43 has been taken up. Any further expansion of the bellows, howeverslight, brings the cam 53 under the followers, and the springs 75 forcethe followers toward each other, giving up energy to the cam 53, andsuddenly snapping the rod 39 to its extreme position. The force of thecam followers overcomes the friction of the shoes 48 and suddenly opensthe valve. Thereafter a gradually decreasing pressure gradually lowersthe rod 39 until the edge of the cam 52 is reached, the valve meanwhilebeing held open by the friction shoes. Thereafter the valve is suddenlysnapped closed by any further slight movement of the bellows.

The cam 52 is termed the closing cam and the cam 53 the opening cambecause they perform these functions respectively. The closing cam 52receives energy from the cam followers on closing, but imparts energy tothem on opening. cam receives energy from the followers when opening,but increases their energy, or imparts energy to the followers when thevalve is being closed. Because one cam receives energy when moving inone direction, and the other cam delivers energy when moving in the samedirection, the slope of all the faces of one cam is considered positivewhile the slope of all-the faces of the other cam is considerednegative. I

The cams can be independently removed to permit the substitution of camsof different pitches, or the cams can be independently rotated topresent faces of different pitches to the followers. By properlyselecting the slopes of the positive and negative cams, the intervalbetween the opening and closing pressures can be variedaccording torequirements, while the absolute values of both opening and closingpressures can be coordinately increased or decreased by suitablyadjusting the tension of the springs 75.

The automatic switch 18 is set to operate at low pressures correspondingto the temperatures to be maintained in the evaporator 20. Whenever thetemperature of 20 is above the maximum permissible value, the pressureof the refrigerant will actuate the switch 18 to operate the condensingelement. Under these conditions refrigerant will not be evaporated inthe evaporator 21 unless the valve 26 is open. VVheneverthe valve isopen, the condensing element will reduce the pressure and temperature ofthe evaporator 21 to its lowest permissible value (which is above thesetting of the switch 18) at which point the valve will close to preventfurther refrigeration in 21. If the evaporator 20 should at any time bewithin its normal temperature limits, and the condensing clementconsequently be idle, and the evaporator 21 should become too warm, thepressure in 21 will open the valve and allow the high pres- Converselythe opening sure to be communicated to the. conduit 11 and switch 18.Since this hi h pressure is above the value which closes t e switch, theswitch will be operated immediately to start the condensing element.Refrigerant will then be withdrawn from both evaporators until both havereached their minimum permissible temperature. If the evaporator 21reaches its minimum temperature first, the

valve 26 will close to prevent further refrigeration, and the condensingelement will continue to refrigerate the evaporator 20. If, however, theevaporator 20 should reach its minimum temperature first, the valve willremain open, and the. pressure of the refrigerant evaporated in 21 willkeep the switch open. However, since each evaporator con tains arelatively large quantity of liquid rerefrigerant, whose pressurecorresponds to its temperature, the rates of evaporation of the liquidwill correspond with the pressures. Hence refrigerant will be evaporatedrapidly in 21 and quickly reduce its temperature, whereas refrigerantwill be evaporated but slowly in 20, and thus its temperature will notbe reduced to a value appreciably below its normal minimum value.

\Vhile the form of embodiment of the invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. A snap-acting control device comprising in combination an actuatoradapted to move between two extreme positions in response to gradualchanges in a condition to be controlled, a control element having twoposi tions, and means for moving the element suddenly from one positionto the other including a lost motion connection between the actuator andelement, a cam of positive slope and a cam of negative slope on theactuator, and a cam follower, the cam of positive slope being adapted toincrease the potential energy of the cam follower during movement of theactuator in a given direction and the cam of negative slope beingadapted to receive energy from the cam follower during further movementin the same direction, and the cam of negative slope being adapted toincrease the potential energy of the cam follower durin movement in theopposite direction, and t e cam of positive slope being adapted toreceive energy from the cam follower during further movement in said.opposite direction, said cams being independently removable.

. 2. A snap-acting control device compris ing in combination an actuatoradapted to move between twoextreme positions in response to gradualchanges in a condition to be controlled, a control element having twopositions, and means for moving the element suddenly from one positionto the other including a lost motion connection between the actuator andelement, a cam of positive slope and a cam of negative slope on theactuator, and a cam follower, the cam of positive slope being adapted toincrease the potential energy of the cam follower during movement of theactuator in a given direction and the cam of negative slope beingadapted to receive energy from the cam follower during further movementin the same direction, and the cam of negative slope being adapted toincrease the potential energyof the cam follower during movement in theopposite direction, and the cam of positive slope being adapted toreceive energy from the cam follower during further movement in said opvposite direction, said cams having portions of different slopes andbeingindependently adjustable to vary independently the positive andnegative slopes presented to the cam follower.

3. A snap-acting control device comprising in combination an actuatoradapted to move between two extreme positions in response to gradualchanges in a condition to be controlled, a control element having twopositions and means for moving the element suddenly from one position tothe other includtuator and the element, a cam on the actuator, and a camfollower, said cam having portions of different slopes and beingadjustable on said actuator to present different portions to said camfollower.

4. A snap-acting control device comprising in combination an actuatoradapted to move between two extreme positions in response to gradualchanges in a condition to be controlled, a control element having twopositions and means for moving the element suddenly from one position tothe other including a lost motionconnection between the actuator and theelement, a cam on the actuator and a cam follower, said cam having 'ofpairs of opposed faces, the slope of the faces in each pair being thesame and the slopes of the pairs being different, and a pair of camfollowers adapted to cooperate with opposed faces, said cam beingadjustable to present different pairs of faces to the camfollowers.

6. A snap-acting control device comprising in combination an actuatoradapted to move ing a lost moti'on connection between the acbetween twoextreme positions in response to gradual changes in a condition to becontrolled, a control element having two positions and means for movingthe element suddenly from one position to the other including a lostmotion connection between the actuator and element, a cam having opposedfaces,.=a" pair of cam followers adapted to cooperate with the faces,means for urging the cams against the faces and means for equalizingbetween the two followers the pressure on the cams.

7. A snap-acting control device comprising in combination an actuatoradapted to move between two extreme positions in re sponse to gradualchanges in a condition to be controlled, a control element having twopositions, and means for moving the element suddenly from one positionto the other including a lost motion connection between the actuator andelement, a cam of positive slope and a cam of negative slope on theactuator, and a cam follower, the cam of positive slope being adapted toincrease the potential energy of the cam follower during movement of theactuator in a given direction and the cam of negative slope beingadapted to receive energy from the cam follower during further movementin the same direction, and the cam of negative slope being adapted toincrease the potential energy of the cam follower during movement in theopposite direction, and the cam of positive slope being adapted toreceive energy from the cam follower during further movement in saidopposite direction, said cams being independently adjustable to vary theinterval between the maximum and minimum values of the condition to becontrolled, and means for coordinately adjusting the maximum and minimumvalues to be controlled including means for varying the resistance tomovement offered by said cam follower.

8. A snap-acting control comprising in combination a movable actuatorhaving two extreme positions and being adapted to move gradually fromone extreme position to a predetermined point in response to gradualchanges in a condition to be controlled and to move suddenly from saidpredetermined point to the other extreme position, a movablecontrolelement having a lost motion connection with the actuator andfriction means for normally preventing movement of the control element,said actuator beingadapted to overcome said friction means.

9. A snap-acting control comprising in combination a movable actuatorhaving two extreme positions and being adapted to move gradually fromone extreme position to a predetermined point in response to gradualchanges in a condition to be controlled and to move suddenly from saidpredetermined point to the other extreme position, a movable controlelement having a lost motion connection with the actuator, a guidewayfor the control element, a friction shoe carried by the control elementand a sprin for urging the friction shoe into contact wiai the guideway.

10. A snap-acting control device comprising in combination an actuatoradapted to move between two extreme positions in response to gradualchanges in a condition to be controlled, a control element having twopositions, and means for moving the element suddenly from one positionto the other including a lost motion connection between the actuator andelement, a cam of positive slope and a cam of negative slope on theactuator, and a cam follower, the cam of positive slope being adapted toincrease the potential energy of the cam follower during movement of theactuator in a given direction and the cam of negative slope beingadapted to receive energy from the cam follower durin further movementin the same direction, and the cam of negative slope being adapted toincrease the potential energ of the cam follower during movement in theopposite direction, and the cam of positive slope being adapted toreceive energy from the cam follower during further movement in saidopposite direction, said cams being independently removable, and meansfor normally preventing movementof said control element, said actuatorbeing adapted to overcome said means.

1].. A snapwacting control device comprising in combination an actuator,a pressure responsive motor adapted to move the actuator between twoextreme positions in response to gradual changes in pressure, a controlelement-having two positions and means for moving the element suddenlyfrom one position to the other including a lost motion connectionbetween the element and the actuator, friction means normally preventingmovement of the element, the actuator being adapted to overcome thefriction means, an opening cam and a closing cam on the actuator, eachof said cams having a plurality of pairs ofopposed faces, the faces ineach pair having the same slopes and the slope of the pairs beingdifferent, a pair of cam followers, means for urging the followers intocontact with opposed faces, means for equalizing between the camfollowers the pressure on the faces, the cams being adjustable topresent different-facesto the cam followers to adjust the intervalbetween the pressure at which the motor moves the element to one extremeposition and the pressure at which the motor moves the element to theother extreme position, and means for adjusting pressure of the camfollowers on the cams to coordinately vary said pressures.

In testimony whereof I hereto aflix my signature.

OLAF C. OLSEN.

